<!DOCTYPE html>

<html lang="en">

<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title> hello world </title>
    <script src="https://unpkg.com/vue@next"></script>
</head>

<body>
    <div id="root"></div>
</body>

<script>
    Vue.createApp({
        data() {
            return {
                content: 1,
            }
        },
        mounted() {
            console.log('mounted');

            setInterval(() => {
                this.$data.content += 1;
            }, 1000)
        },
        template: '<div>{{content}}</div>'
    }).mount('#root');
</script>

</html>